FIG. 1 shows a schematic view of a bicycle crank axle 10 which is disclosed by this inventor of the present invention in the U.S. Pat. No. 5,549,396. The bicycle crank axle 10 is provided at both ends thereof with a tapered sleeve 20, and a tapered bearing 30 which is fitted over the tapered sleeve 20 and is engaged with a tapered fixation seat 31.
Such a bicycle crank axle 10 as prior art described above is susceptible to idle running in view of the tapered bearings 30 which do not work well with the steel balls or the non-tapered frame tube. In addition, the crank axle 10 is vulnerable to wear.